What is backing plates?

In thin film manufacturing of Liquid Crystal Panels and Semiconductors, a method of sputtering evaporates the metal and generates a circuit. The metal (target material) that evaporates when sputtering is very hot, so it cools and proceeds with the production process.

The backing plate is used to cool the target material.
The backing plate is used in the vacuum chamber of the sputtering device, and the material is made of copper and has a water-cooled jacket structure.

Our backing plates

The water-cooled jacket is formed by joining the main body and the water-cooled lid with vacuum brazing, electron beam welding, Friction Stirring Welding, etc.
In particular, Friction Stirring Welding system of our own facility is considered to be more reliable at the junction than melt welding when it comes to bonding nonferrous metals, and is actually used for bonding the bodies of aircraft and Shinkansen trains.

Kyoyu’s backing plates respond to various types of shapes ranging from round to angular shapes, and advanced distortion correction technology enables surface cutting after welding to maintain a constant thickness of the water-cooled lid, contributing to improved cooling efficiency.

Production range

Material Aluminum, Stainless steel, Copper
Joining methods Tig welding, Vacuum brazing, Electron beam welding (EBW), Friction stirring welding (FSW)
Maximum size that can be manufactured Circular form:φ800mm
Rectangular form:Width 1,000 mm、Length 2,000 mm
Structure The jacket structure having grooves covering the lid from the above is main.
Shape Compatible with various external shapes and complex waterway shapes
Specifications All manufactured parts are custom-made with customer specifications
Notes We do not provide purchasing, sales, or bonding services for target materials.

Production examples

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We can handle a wide range of services from technical consultation on product production and processing to consultation on specific estimates.

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Backing Plates by FSW(Friction Stir Welding)

Advantage 1: Uniform Cooling Performance

In order to make the lid thickness uniform after the surface finishing process, as shown in the figure, a dedicated press machine is used to correct the warping and distortion of the base material and the lid. After that, the finishing process is carried out. A uniform lid thickness will be realized by this process. If the thickness of the lid is uniform, the distance from the groove (cooling channel) to the top surface of the lid (contact face) is also constant, and it has a cooling performance with no variation.

If the finishing process is done from the contact area without correction with a press machine, the thickness of the lid at the time of completion will change depending on the place as shown in the figure. If there is a thick part and a thin part of the lid with respect to the groove (cooling channel), a temperature difference will be created due to the difference in thickness, and as a result, the cooling performance will vary.

Advantage 2: High Joints Reliability

The joints by FSW can be made with the lid onto the base material closely without gaps.
In fusion welding by an electron beam that heats the material above the melting point temperature, there are concerns in the reliability of the joints due to slag and bubble. And in the brazing process, there are concerns about joint failure due to brazing shortage. On the other hand, FSW, which is a solid phase joining, is heated and softened as a solid without melting, and then pressurized to be joined. So there is almost no slags, air bubble and thus joining defects will rarely occur. Therefore, it has realized high reliability at the junction of the base material and the lid.

Advantage 3: High-Mix Low-Volume(HMLV) Production

The parts used in the manufacturing equipment in production line are different from the ones in mass-produced products, and equipment-specific customized ones are also required. Since FSW is used utilizing a dedicated processing equipment, it can be used for high-mix low-volume production.
Our processing equipment is a specially made hybrid machine that can perform cutting and joining (FSW) on the same machine. We have an integrated production system from machining to joining, and we can manufacture products that guarantee high quality.

Advantage 4: High Material Strength

FSW can maintain high material strength. In the case of brazing, the entire material will become hot during the brazing process and the base material will soften. In some cases, the more bend with own weight, the weaker the strength of the material becomes. On the other hand, FSW is a solid phase joining, and the base material does not soften because there is no need to heat the entire material. In addition, the joining part has a material strength equal to or greater than that of the base material. In this way, FSW is a joining method that does not reduce the material strength of the base material.

First, please feel free to contact us.

We can handle a wide range of services from technical consultation on product production and processing to consultation on specific estimates.

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Things to consider when designing

1 Materials


The cost of aluminum is low that is about one-third of copper. The thermal conductivity shows a good value although it is about half compared to 236W · m-1 · k-1 and copper 398W · m-1 · k-1. On the other hand, Young’s modulus is about 70GPa, which is low and easy to deform compared to about 115GPa in copper and 196GPa in stainless steel. Therefore, if the usage environment with a relatively low load on the backing plate or if the heat generation is relatively low as low as copper, it can be produced at a low cost.

Material Young’s modulus in ksi
C10100(OEE copper) 16700
C11000(ETP copper) 16700
C18200 Chromium copper 18900
Molybdenum 47700
304 Stainless Steel 28500
6061 Aluminium 10000



The copper backing plate using oxygen-free copper (C1020), which has the lowest oxygen content among pure copper is a mainstream. As for Tough- pitch copper materials, there are some concerns of generating gases in a vacuum environment. The thermal conductivity of copper has a high value of 398W · m-1 · k-1, and it is a relatively easy material to process. Copper materials are suitable for places where high heat dissipation is required or when complex processing is required. The Young’s modulus is also about 115GPa, which is high in strength and hard to deform. On the other hand, due to pure copper being a difficult-to-cut material, it is a material that requires high processing technology.

Stainless steel

Stainless steel has a thermal conductivity of 17W · m-1 · k-1 and that is not so good compared to copper but the Young’s modulus is 196GPa , which is higher than about 115GPa for copper.
On the other hand, it is not suitable for complex shapes and/or fine shapes due to poor processability.

2 Thermal Conductivity

During the sputtering process, the surface of the sputtering target will be hot, so the heat generated must be continued to be cooled. Therefore, backing plates are required to be made of materials with high thermal conductivity in order to efficiently cool the heat generated on the backing plate
In addition, if there is a temperature difference between the sputtering target and the backing plate, thermal stress will be generated, and cracks and peeling will occur with brittle materials, so it is also important to use materials with high thermal conductivity to equalize them.
Generally, thermal conductivity is material-specific, so if you want high cooling efficiency, a material with high thermal conductivity will be chosen.

3 Mechanical Strength

The backing plate also requires mechanical strength. There are two types of cooling methods for the backing plate in sputtering, a direct method to cool the backing plate itself and an indirect method that cools the device and cools it by heat conduction.
In the case of the direct method, high pressure is applied to the backing plate, which can cause the backing plate to warp and at the same time, warping, cracking and peeling of the sputtering target on the backing plate may occur.
Therefore, the backing plate requires a high strength (Young’s modulus) that is difficult to deform even if high pressure occurs. Since the Young’s modulus is material-specific, if you want to minimize the warping caused by cooling, you will choose a material with a high Young’s modulus.

Types of Backing Plates

Jacket Water Cooling Type

The jacket-shaped backing plate is divided into a base part and a lid. A part of the base part is formed with grooves through where cooling water flows . The waterway of the base part is covered by the lid. The base part material and the lid are joined by brazing or friction stir welding, etc.

One Body Type

The sputtering target and integrated backing plate are manufactured with the same material as the sputtering target and backing plate. Since it is integrated, it has the advantage of reducing the target’s replacement time as much as possible and the manufacturing costs can be reduced. On the other hand, because it is an integrated type, there is also a concern about warping during sputtering due to lack of strength.

Process of Backing plates fabrication

STEP 1: Forming Groove

Process a pocket-shaped groove that receives a lid on the base part. A groove that is the passage of cooling water is created in this groove by cutting process.

STEP 2: Manufacturing a Lid

Separately, make a lid to cover the pocket-shaped groove .

STEP 3: Join the Lid

Join the base and the lid.Fit into a pocket-shaped groove. After that, the base and the lid are joined using one of the joining methods such as electron beam welding, brazing, or friction stir welding.

STEP 4: Finishing

Finish the surface of the joint face of the base and the lid. Since unevenness and distortion occur during joining, the joint surface is finished smoothly by cutting process.

First, please feel free to contact us.

We can handle a wide range of services from technical consultation on product production and processing to consultation on specific estimates.

Contact us